#include<cstring>
#include<algorithm>
#include<cstdio>
#include<queue>
using namespace std;
int main()
{
	int n;
	priority_queue<unsigned int>q;
	scanf("%d",&n);
	for(int i=1;i<=n/2+1;i++)
	{
		int x;
		scanf("%u",&x);
		q.push(x);
	}
	for(int i=n/2+2;i<=n;i++)
	{
		int x;
		scanf("%d",&x);
		q.push(x);
		q.pop();
	}
	if(n%2)printf("%0.1lf\n",(double)q.top());
	else
	{
		unsigned int x,y;
		x=q.top();q.pop();
		y=q.top();
		printf("%0.1lf",(x+y)/2.0);
	}
	return 0;
}

